Valve and Turtle Rock Studios announce development of Left 4 Dead, a cooperative
multiplayer action game using the Source engine that's slated for release next
year:

November 20, 2006 - Turtle Rock Studios and Valve today announce
Left 4 Dead, a co-operative multiplayer action game from the makers of
Counter-Strike.

"By leveraging its industry-leading AI technology and years of Counter-Strike
development experience, Turtle Rock is building upon the elements that make
Counter-Strike successful and applying them to Left 4 Dead," said Gabe Newell,
co-founder and president of Valve. "What Counter-Strike did for multiplayer
action games, Left 4 Dead will do for co-op games."

Left 4 Dead is built atop the most advanced version of the Source Engine and
introduces version 2 of Turtle Rock's artificial intelligence (A.I.) technology.